Download 1A Step-Down Voltage Regulator

LM1575/LM2575/LM2575HV
SIMPLE SWITCHER ® 1A Step-Down Voltage Regulator
General Description
Features
The LM2575 series of regulators are monolithic integrated
circuits that provide all the active functions for a step-down
(buck) switching regulator, capable of driving a 1A load with
excellent line and load regulation. These devices are available in fixed output voltages of 3.3V, 5V, 12V, 15V, and an
adjustable output version.
n 3.3V, 5V, 12V, 15V, and adjustable output versions
n Adjustable version output voltage range,
1.23V to 37V (57V for HV version) ± 4% max over
line and load conditions
n Guaranteed 1A output current
n Wide input voltage range, 40V up to 60V for HV version
n Requires only 4 external components
n 52 kHz fixed frequency internal oscillator
n TTL shutdown capability, low power standby mode
n High efficiency
n Uses readily available standard inductors
n Thermal shutdown and current limit protection
n P+ Product Enhancement tested
Requiring a minimum number of external components, these
regulators are simple to use and include internal frequency
compensation and a fixed-frequency oscillator.
The LM2575 series offers a high-efficiency replacement for
popular three-terminal linear regulators. It substantially reduces the size of the heat sink, and in many cases no heat
sink is required.
A standard series of inductors optimized for use with the
LM2575 are available from several different manufacturers.
This feature greatly simplifies the design of switch-mode
power supplies.
Other features include a guaranteed ± 4% tolerance on output voltage within specified input voltages and output load
conditions, and ± 10% on the oscillator frequency. External
shutdown is included, featuring 50 µA (typical) standby current. The output switch includes cycle-by-cycle current limiting, as well as thermal shutdown for full protection under
fault conditions.
Typical Application
Applications
n
n
n
n
Simple high-efficiency step-down (buck) regulator
Efficient pre-regulator for linear regulators
On-card switching regulators
Positive to negative converter (Buck-Boost)
(Fixed Output Voltage
Versions)
01147501
Note: Pin numbers are for the TO-220 package.
SIMPLE SWITCHER ® is a registered trademark of National Semiconductor Corporation.
© 2004 National Semiconductor Corporation
DS011475
www.national.com
LM1575/LM2575/LM2575HV Series SIMPLE SWITCHER 1A Step-Down Voltage Regulator
August 2004
LM1575/LM2575/LM2575HV
Block Diagram and Typical Application
01147502
3.3V, R2 = 1.7k
5V, R2 = 3.1k
12V, R2 = 8.84k
15V, R2 = 11.3k
For ADJ. Version
R1 = Open, R2 = 0Ω
Note: Pin numbers are for the TO-220 package.
FIGURE 1.
Connection Diagrams
(XX indicates output voltage option. See Ordering Information table for complete part
number.)
Straight Leads
5–Lead TO-220 (T)
Bent, Staggered Leads
5-Lead TO-220 (T)
01147522
Top View
LM2575T-XX or LM2575HVT-XX
See NS Package Number T05A
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01147523
Top View
2
01147524
Side View
LM2575T-XX Flow LB03 or
LM2575HVT-XX Flow LB03
See NS Package Number T05D
16–Lead DIP (N or J)
24-Lead Surface Mount (M)
01147525
*No Internal Connection
Top View
LM2575N-XX or LM2575HVN-XX
See NS Package Number N16A
LM1575J-XX-QML
See NS Package Number J16A
01147526
*No Internal Connection
Top View
LM2575M-XX or LM2575HVM-XX
See NS Package Number M24B
TO-263(S)
5-Lead Surface-Mount Package
01147529
Top View
01147530
Side View
LM2575S-XX or LM2575HVS-XX
See NS Package Number TS5B
Ordering Information
Package
NSC
Standard
High
Temperature
Type
Package
Voltage Rating
Voltage Rating
Range
Number
(40V)
(60V)
5-Lead TO-220
T05A
Straight Leads
5-Lead TO-220
T05D
LM2575T-3.3
LM2575HVT-3.3
LM2575T-5.0
LM2575HVT-5.0
LM2575T-12
LM2575HVT-12
LM2575T-15
LM2575HVT-15
LM2575T-ADJ
LM2575HVT-ADJ
LM2575T-3.3 Flow LB03
LM2575HVT-3.3 Flow LB03
Bent and
LM2575T-5.0 Flow LB03
LM2575HVT-5.0 Flow LB03
Staggered Leads
LM2575T-12 Flow LB03
LM2575HVT-12 Flow LB03
LM2575T-15 Flow LB03
LM2575HVT-15 Flow LB03
LM2575T-ADJ Flow LB03
LM2575HVT-ADJ Flow LB03
3
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LM1575/LM2575/LM2575HV
Connection Diagrams (XX indicates output voltage option. See Ordering Information table for complete part
number.) (Continued)
LM1575/LM2575/LM2575HV
Physical Dimensions
inches (millimeters) unless otherwise noted (Continued)
TO-263, Molded, 5-Lead Surface Mount
Order Number LM2575S-3.3, LM2575HVS-3.3, LM2575S-5.0, LM2575HVS-5.0, LM2575S-12,
LM2575HVS-12, LM2575S-15, LM2575HVS-15, LM2575S-ADJ or LM2575HVS-ADJ
NS Package Number TS5B
www.national.com
26
inches (millimeters) unless otherwise noted (Continued)
Bent, Staggered 5-Lead TO-220 (T)
Order Number LM2575T-3.3 Flow LB03, LM2575HVT-3.3 Flow LB03,
LM2575T-5.0 Flow LB03, LM2575HVT-5.0 Flow LB03,
LM2575T-12 Flow LB03, LM2575HVT-12 Flow LB03,
LM2575T-15 Flow LB03, LM2575HVT-15 Flow LB03,
LM2575T-ADJ Flow LB03 or LM2575HVT-ADJ Flow LB03
NS Package Number T05D
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significant injury to the user.
2. A critical component is any component of a life
support device or system whose failure to perform
can be reasonably expected to cause the failure of
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LM1575/LM2575/LM2575HV Series SIMPLE SWITCHER 1A Step-Down Voltage Regulator
Physical Dimensions